Relay Coordination in Power Systems with Penetration of Distributed Sources

Abstract

A comprehensive OCR coordination scheme has been developed in this research paper. An industrial power system based on renewable energies has been taken for case study which contains a 3 MW PV plant, a 2 MW DFIG based wind turbine and various inductive motor loads at an 11 kV distribution bus. The fault current contribution of inverter-based resources (IBRs) and induction motors in both directions makes the conventional relay grading methods ineffective. A thorough ETAP simulation model is created, which includes the impedances of transformers, parameters of cables, ratios of CT, and modelling of IEC 60255-151 Std. Inverse (SI) characteristic of the relay. To simultaneously optimize time-multiplier settings (TMS) and the pickup currents (Ipu) of six directional overcurrent relays, two meta-heuristic algorithms, namely Genetic Algorithm (GA) and Particle Swarm Optimization (PSO), are executed in MATLAB. The results show that both of the algorithms are able to achieve full coordination with CTI of 0. 3 s. PSO converges 18. 6% faster than GA. According to the conventional definite-time grading, the total primary relay operating time has been minimized by 34. 7%. Cross-validation is done using ieee 39-bus benchmark fault data. Overcurrent relay coordination of inverter-based resources in a DFIG wind turbine and an induction motor as per IEC 60255-151 using ETAP, GA and PSO.